Stock level not changing

[squawk]

I think this is a basic question but I can't find an anwser.
Once a product is brought the stock levels are not changing.
I'm not referring to (at this stage) child products but main products.
The 'Action when a Product is Out of Stock' action is set to 'Notify Me' and 'Send low stock notification' but no change.
It must be a straight anwser, can anyone point me in the correct direction.

Using VM 2.0.20b in Joomla 2.5.9

Cheers